The proposed studies aim to characterize the memory impairments produced by damage to the medial temporal lobes by examining recognition memory in amnesic patients suffering from cardiac arrest and stroke. Recent research has revealed that although these patients exhibit debilitating memory impairments for a broad range of materials, recognition memory for some types of information can remain well preserved. These results challenge our current theories of memory and the medial temporal lobes, and indicate that the memory impairments seen in amnesia are not as general as previously thought. The current proposal aims to determine the factors that are responsible for the impaired and unimpaired memory abilities of these patients by examining their memory deficits in tests of item recognition for a wide variety of stimuli (e.g., faces, scenes, complex visual and auditory stimuli), as well as across a range of different types of associations (e.g., pairings of visual and auditory materials, objects and scenes etc). The studies will be first to examine the effects of several critical factors that have not been previously studied in amnesia. Moreover, the proposed studies make use of sophisticated measurement methods such as receiver operating characteristic analysis that will provide precise quantification of the memory abilities of these patients, not possible with previous methods. Finally, the studies will provide a unique opportunity to directly test novel theoretical perspectives, and thus promises to lead to significant advances in our understanding of normal and abnormal memory functions in the human brain. PUBLIC HEALTH RELEVANCE: The proposed studies will advance our understanding of the cognitive and neural substrates of recognition memory by examining the effects of several factors that have never been directly examined in amnesia;they will allow us to evaluate whether the leading memory theories are able to the overcome the challenges posed by recent empirical discoveries;and they will play a critical role in shaping future recognition models of the medial temporal lobes by directly testing core predictions derived from new theoretical approaches. In addition, the results will be essential in providing a clearer delineation of the memory impairments suffered by various neurological populations by allowing us to more accurately identify their deficits and their preserved memory abilities, and thus will lay the foundation for more accurate diagnosis and treatment of memory-impaired neurological patients (e.g., stroke, cardiac arrest, Alzheimer's Disease and Schizophrenia).